feat: day 10

2015/Day10.scala

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+package day10
+
+import scala.io.Source.fromFile
+
+val groupNums = raw"(.)\1*".r
+
+def nextNums(s: String) = groupNums
+  .findAllIn(s)
+  .map { xs => s"${xs.length}${xs.head}" }
+  .mkString
+
+def solution(input: String)(n: Int) =
+  (1 to n).foldLeft(input) { (acc, _) => nextNums(acc) }.length
+
+@main def main() =
+  val input = fromFile(".cache/10.txt").mkString.trim
+  val solver = solution(input)
+
+  val part1 = solver(40)
+  println(part1)
+
+  val part2 = solver(50)
+  println(part2)

2015/Day10.test.scala

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+import munit.FunSuite
+import day10.*
+
+class Day10Tests extends FunSuite:
+  test("Part 1"):
+    Seq("1", "11", "21", "1211", "111221", "312211")
+      .sliding(2)
+      .map { case Seq(a, b) => assertEquals(nextNums(a), b) }